1. Technical Field
The present invention relates to a method of manufacturing aldehyde by oxidizing a primary alcohol into the corresponding aldehyde, and more particularly, to an improvement in said method using a heterogeneous catalyst.
2. Background Art
In general, a serious difficulty is involved in the production of aldehyde by the oxidation reaction of primary alcohol. This difficulty is in good contrast to the ketone production by the oxidation of secondary alcohol, which can be achieved relatively easily by utilizing the Oppenauer oxidation.
Known methods of producing an aldehyde by the oxidation of a primary alcohol include, for example, the Collins oxidation disclosed in Tetrahedron Letters, p. 3363, 1968 and the DMSO-DCC method disclosed in Journal of the American Chemical Society, Vol. 85, 1963. However each of these known methods necessitates troublesome operations for purifying the product after the reaction. In addition, it is difficult to recover and re-use the reaction reagent, giving rise to serious air pollution or water contamination problems.
When it comes to the Oppenauer oxidation with a homogeneous catalyst system, a method of converting a primary alcohol into the corresponding aldehyde using aluminum isopropoxide as a catalyst in the presence of quinone acting as an oxidizing agent is known, as disclosed in Organic Reactions, Vol. 6, p. 207, 1951. However, it is difficult to re-use the catalyst in this method. Also, troublesome operations are required for the reaction and for the purifying step after the reaction.
In order to overcome the problems noted above, proposed in Published Unexamined Japanese Patent Application No. 1-151532 is a method of producing aldehyde at a high selectivity and a high yield, in which alcohol is reacted with a solid bromite in the presence of alumina or silica gel acting as a heterogeneous catalyst. However, this method is applicable only to benzyl alcohol and derivatives thereof, and thus, is not of sufficient practical value.